This section is intended to introduce the reader to various aspects of art, which may be related to various aspects of the present invention that are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present invention. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.
An auto-stereoscopic display is a display device providing a 3D effect that can be perceived without any glasses. The simplest auto-stereoscopic display devices provide stereoscopic 3D rendering with only two views, they are based on parallax barriers. Multi-view auto-stereoscopic display devices based on lenticular network are able to generate more than 2 views to allow the viewer to be placed at different position seeing stereoscopic content. In this case, a network of lenses is added in front of the RGB sub-pixel matrix of a display. Thanks to these lenses, the light generated by the different sub-pixel R, G or B is generated in different directions, depending on the position of the sub-pixel relatively to the lens. When a user is placed in front of this display device, at a certain distance and position, he will receive on each eye only the light generated by some sub-pixels. To perceive the 3D effect without glasses, the user must receive on one eye the light of the sub-pixels generating a 3D view, and on the other eye the light of the sub-pixels generating another 3D view adjacent to the first one. The FIG. 1 presents a simple scheme of multi-view auto-stereoscopic display device generating 8 views, according to the state of the art. In this example, the red (noted R on FIG. 1) sub-pixel 0 and the blue (noted B in FIG. 1) sub-pixel 8 will generate the view V7. The green (noted G on FIG. 1) sub-pixel 1 and the red sub-pixel 9 will generate the view V6, and so on up to the view V0 generated by the green sub-pixel 7 and the red sub-pixel 15. With such a scheme, a RGB pixel generates the information corresponding to three different views.
A preferred scheme, disclosed in FIG. 2, is to transmit some of the views with some associated disparity maps to an auto-stereoscopic display, and then such auto-stereoscopic display interpolates the missing views in order to provide the appropriated number of views that the auto-stereoscopic display supports. At the acquisition side, if we consider a four cameras system we must then transmit four views and four associated disparity map. The display is the able to interpolate the missing views.
However, a drawback of this scheme is that the amount of data to be transmitted (e.g. the images (which are images of a same scene that were generated by several cameras positioned in several position corresponding to a view, such images being not necessarily interpolated), as well as the associated disparity maps) is quite high. Indeed, the more views the auto-stereoscopic display received from a device providing the images and the disparity maps, the heavier the bandwidth load is. Such issue can be critical in some context in which the bandwidth management is a difficult issue to handle.
In order to solve this issue, one skilled in the art would have reduced arbitrarily the number of transmitted multi-views camera images, as well as the corresponding disparity map. Then, by using a stereo-to-multiview conversion technique (as for example the one depicted in the document entitled “Fully Automatic Conversion of Stereo to Multiview for Autostereoscopic Displays” by C. Riechert et al., published in the proceedings of the conference IBC 2012), the auto-stereoscopic display could still display the same number of views. The reduction is set up when a monitoring of the bandwidth provides information indicating that the bandwidth is saturated (or beyond a pre-defined level). In a variant, in order to solve this issue, one skilled in the art would have reduced only the number of transmitted disparity maps, as the missing (i.e. not received) disparity maps can be computed within the auto-stereoscopic display.
The proposed technique proposes an alternative to these techniques.